Effects of carbide grain growth inhibitors on the microstructures and mechanical properties of WC–SiC–Mo2C hard ceramics

• Cr3C2, NbC, or ZrC was added WC–SiC–Mo2C ceramics sintered at 1600 °C using SPS.
• Dense carbide-added WC–SiC–Mo2C ceramics were obtained at 1600 °C.
• Coarse plate-like WC grains disappeared with Cr3C2, NbC, or ZrC addition.
• High hardnesses were measured for the carbide-added WC–SiC–Mo2C ceramics.
• ZrC light doping improved the fracture toughness without reducing the hardness.

Cr3C2, NbC, or ZrC was added to WC–4.85 mol% SiC–1 mol% Mo2C ceramics and sintered at 1600 °C using a resistance-heated hot-pressing machine. Dense ceramics containing 0–0.3 mol% Cr3C2, 0–3 mol% NbC, and 0–10 mol% ZrC were obtained. An additive carbide-based solid solution was observed only for NbC and ZrC additions. The coarse plate-like WC grains disappeared with the addition of Cr3C2, NbC, or ZrC and the ceramics consisted of fine equiaxed WC grains. Higher hardnesses, 19.4–21.8 GPa, were measured for the carbide-added WC–SiC–Mo2C ceramics than for the WC–4.85 mol% SiC ceramics because of the disappearance of coarse plate-like grains. The addition of a small amount of ZrC improved the fracture toughness without reducing the hardness.